Process for the conversion or cracking of high boiling hydrocarbon oils into low boiling hydrocarbon oils



June 11, 1935. s u

PROCESS FOR THE CONVERSION OR CRACKING OF HIGH BOILING HYDROCARBON OILSINTO LOW BOILING HYDROCARBON 0111s Original Filed July 24, 1950 INVENTORJEAN DELATTRE SEGUY BYF ZM ATTORNEY Patented June 11, 1935 PATENT OFFICEPROCESS FOR THE CONVERSION OB CRACKING OF HIGH BOILING HYDRO- CARBONOILS INTO LOW BOILING HYDROGARBON OIL Jean Delattre Seguy, Chicago,111.,

Universal Oil Products Company, a corporation of South Dakota assignorto Chicago, 111.,

Application July 24, 1930, Serial No. 470,342

- Renewed February 8, 1934 5 Claims.

This invention contemplates the provision of a process for theconversion or cracking of high boiling hydrocarbon oils into low boilinghydrocarbon oils. 7

The invention relates to a process wherein hydrocarbon oils aresubjected to a primary cracking reaction under proper conditions, thevapors and the residue resulting from the cracking being separatelytreated. The specific form of process to which the invention relatescomprises the introduction of heavy hydrocarbon oil into a heating coilin which the oil is subjected to pressure and temperature conditionssufliciently elevated to induce cracking, the oil then being subjectedto reaction in a primary reaction zone, the vapors evolved therefrombeing withdrawn and subjected to dephlegmation with the separation 'ofthe lower boiling hydrocarbons in the form of vapors from the higherboiling hydrocarbons which are obtained as a reflux conden sate. Theunvaporized residue from the primary reaction zone is distilled by itscontained heat in a flashing zone, the vapors being withdrawn fortreatment in'a fractionating zone, the lighter 25 fractions therefrombeing condensed, the heavier fractions taking the form of a refluxcondensate.

One of the features of my invention resides in the vapor phase crackingof the reflux obtained 80 by dephlegmation of the vapors withdrawn fromthe primary reaction zone and the return of the products resulting fromthe vapor phase cracking into the primary reaction zone to assist in theconversion of the oil and to regulate the character of theproductobtained in said zone. By

means of the coupling up of this feature of the invention with theprimary cracking system, a gasoline containing high anti-knockproperties may be obtained.

A further feature of my invention resides in the vapor phase cracking ofthe flash reflux condensate and the introduction of the productsresulting therefrom into the primary reaction zone. In accordance withthe provisions of the invention, it is contemplated that the vapor phasecracking of the reflux from the primary dephlegmator and the refluxobtained from the flash distillation step may be carried onsimultaneously in the same vapor phase cracking zone, the relativeproportions of the reflux condensates subjected to vapor phase crackingbeing regulated to any desired extent, the products of the vapor phasecracking being then introduced into the primary reaction zone. Thereflux condensate from the flash distillation step may, if desired, bepassed into direct contact with; the vapors being treated in the primarydephlegmating zone, or they may be passed directly to the vapor phasecracking zone.

My invention provides further for the indirect contact of the chargingoil with the vapors arising in the various fractionating zones. Thecharging oil may be passed in indirect contact, therefore, with thevapors which are being treated in the flash distillation zone, and mayalso be passed through a similar indirect heat exchange relationshipwith the vapors in the primary dephlegmating zone. This insures theproper cooling of the vapors in said zones with the obtaining of refluxcondensates which may suitably be subjected to vapor phase crackingconditions. A minor portion of the charging oil may, if desired, bepassed in direct contact with the vapors in the flash distillation zonedependent upon the operating conditions of the process.

As a provision of my process, I may divert a portion of the charging oilinto direct contact with the oil emerging from the primary heating zoneor from the vapor phase cracking zone for the purpose of checkingcracking to any desired extent. The cooling of the oil coming from theheating zone in this manner and its contact in the reaction zone withthe oil from the vapor phase cracking zone serves to check or controlthe cracking of the products which are introduced into the primaryreaction zone from the vapor phase cracking zone.

Other improvements and features of my invention will be more fullyunderstood by reference to the drawing showing an apparatus suitable forcarrying out the process of the invention, the drawing beingdiagrammatic and not to scale.

The raw oil charging stock is pumped through line I by means of pump 2into line 3, controlled by valve 4. A portion of the charging stock maybe introduced directly into the flash dephlegmator 1 through line 5,controlled by valve 6. It is desirable, however, that all or the majorportion be fed through line 8, controlled by valve 9, into in-v directheat exchanger I 0 located in flash dephlegmator 1. The raw charging oilis then fed into indirect heat exchanger l I located in primary Ydephlegmator l2, causing partial condensation of the vapors arisingtherein, the reflux condensate so formed being further subjected tocracking conditions as will be hereinafter described. The raw oil thenpasses through line 53 and valve 10 into heating element l4 located-infurnace setting 125. A portion of the raw oil may be diverted throughline l6, controlled by valve l1, into the transfer line I8 of theheating element I4. The raw oil passes through control valve I9 intoreaction chamber 28. The vapors leaving reaction chamber 28 pass throughline 2|, controlled by valve 22, into the dephlegmator I2 whereinindirect heat exchange occurs between the ascending vapors and the rawoil as heretofore described. Additional cooling is also eifected, aswill be hereinafter described.

The reflux condensate from the dephlegmator passes through line 23,controlled by valve 24, into hot oil pump by which it is pumped by line26, controlled by valve 21, into secondary heating element 28 located infurnace setting 29. The temperature in this heating element is elevatedso that substantially vapor phase cracking occurs therein. The vaporsleaving heating element 28 pass through line 69, controlled by valve 30,into reaction chamber 20.

The final vapors leaving dephlegmator I2 pass through line 3 I,controlled by valve 32, into cooler and condenser 33, the distillatetherefrom together with gases passing through line 34,. controlled byvalve into receiver 36. The distillate from receiver 36 is withdrawnthrough line 31, controlled by valve 38. The gases in receiver 36 arewithdrawn by line 39, controlled by valve 46. A portion of thedistillate may be recirculated to the dephlegmator I2 through line 4|,controlled by valve 42, by means of pump 43 and through line 44,controlled by valve 45. The purpose of this is to assist in cooling thevapors arising in dephlegmator I2 to condense out the heavier portionstherein, the reflux condensate so formed being subjected to conversionconditions as previously described.

The unvaporized residue from reaction chamber 20 passes through line 46,controlled by valve 41, into the flash distilling-chamber 48 where owingto the reduction in pressure and the latent or stored heat in theresiduum flashing or vaporization occurs. Unvaporized residual oil maybe withdrawn from chamber 48 through line II and valve I2. The vaporsleaving the flash chamber 48 pass through line 49, controlled by valve50, into flash dephlegmator I. The heavier portions of the vapors arecondensed in flash dephlegmator I owing to the cooling action of the rawoil either by indirect or direct contact. Additional cooling of thevapors in dephlegmator I may be provided, by means of relatively lightoils, such as a part of the distillate collected in receiver 64, ormaterial not heavier than the condensate formed in dephlegmator 1. Thereflux condensate so formed passing through line 5|, controlled by valve52, is pumped by means of pump .53 through line 54 in whole or in partthrough line 55, controlled by valve 56, into the primary dephlegmatorI2 or through line 51, controlled by valve 58, and by means of pump 25through line 26, valve 21 into vapor phase heating element 28 from whereit is discharged through line 69 and valve 30 into the reaction chamber20. A portion of the raw oil, before it enters heating coil I4 may bediverted through line I3, controlled by valve 14, and mixed :in line 69with the products of vapor phase cracking,

whereby their temperature and the degree of conversion may be regulated.

The lower boiling components of the vapors leaving flash dephlegmator Ipass through line 59, controlled by valve 60, into flash cooler and ingin flash receiver 64 may be withdrawn through line 65, controlled byvalve 66. The gases collecting in receiver 64 are withdrawn through line6'1, controlled by valve 68.

While the products from coil 28 may discharge at upper part of chamber20, near the point of introduction of the products from coil I4, it maybe preferable to introduce them at the lower part of chamber 28, wherebythe vapors may bubble through the unvaporized oil maintained at thelower part of said chamber. However, the condition of level or timeelement in the chamber 26, as well as the temperature therein arepreferably controlled by the various means shown so that little or nocarbon forms, and that the residue from the process may be substantiallyfree of B. S. and solids, or may not contain more than 2% thereof.

I may employ equalized pressure on the heating element i4, reactionchamber 20, primary dephlegmator I2, condenser 33 and receiver 36, or Imay employ differential pressures thereon. Preferably, there is areduction in pressure between the reaction chamber 26 and the flashingstill 48. The pressure in heating element 28 may be elevated as desiredby means of pump 25.

I preferably employ temperatures within the cracking range of 800 F. to975 F., more or less, in heating element I4, whereas in heating element28 I preferably employ temperatures ranging from 950 F. to 1250 F., moreor less, although I do not limit myself specifically to these ranges.

As a specific example of the results obtained by the process of myinvention, a 28 A. P. I. gravity topped crude may be processed at atemperature in the heating element I4 of approximately 900 F., under apressure, maintained on the heating element and the reaction chamber 20,of approximately 175 pounds per square inch, the pressure. on theelements I2, 33 and 36 being substantially equalized therewith; thetemperature in vapor phase heating element 28 may be approximately 975F.; the ratio of reflux condensate, including the condensed flashdistillate passing through coil 28 being approximately three times theamount of raw oil charged to-coil I4; the average temperature in thereaction chamber being approximately 875 F., a yield of about 60% ofgasoline was obtained having an anti-knock value of approximately benzolequivalent, that is equivalent to a mixture of straight run Pennsylvaniagasoline and benzol containing 50% of the latter. Approximately 25% of agood fuel oil residue was obtained having less than 2% B. S. andsuspended carbonaceous matter; approximately 5% of pressure distillatebottoms was obtained and the remainder was substantially all gas, asvery little coke was made.

By elevating the temperature in the heating element 28 to 1025 F. andmaintaining all other conditions substantially constant with theexception of the temperature in reaction chamber 28, which was somewhatincreased, and with the exception of a somewhat lower reflux rationresulting from the operation, the gas volume was increased fromapproximately 650 cubic feet per barrel in the previous example toapproximately 850 cubic feet per barrel of raw oil charged in thepresent case. The gasoline yield was reduced to approximately 55% andthe anti-knock value was increased to approximately benzol equivalent. Aheavy asphaltic residual oil was produced and the amount of pressuredistillate bottoms was increased somewhat. The amount of coke formed inthe second case was greater than that in the first. With similarconditions, but by cooling the oil discharging from coil 28 with cooleroil, as shown, so as to lower the temperature of the oil in the chamber20 down to about 875 F., the yield and the anti-knock characteristicsremained about the same, but the residue was rendered more fluid and itscontent in B. S. and solids, as well as the coke formation weresubstantially reduced.

The rate of gas formation was found to be not solely a function oftemperature, but also of time and pressure. The pressure in the heatingelement 28 during the above operations was approximately 200 pounds persquare inch. In other cases where the pressure was reduced on thereaction chamber 20 and the succeeding elements and the pressurelikewise on coil 28 for corresponding temperatures the gas formation wasfound to increase somewhat. The pressure on the flash distillationsystem was maintained at approximately 30 pounds per square inch.

In the above operations only a small portion of the raw oil wasby-passed in direct contact with the vapors in the flash dephlegmator.

The above examples are illustrative only and are not to be considered aslimitations on the scope of the invention.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises passing the oil ina restricted stream through a primary heating zone and heating the sametherein to cracking temperature under sufflcient pressure to maintain asubstantial portion thereof in the liquid phase, discharging the heatedoil into a vapor separating zone and separating the same therein intovapors and unvaporized oil, separately removing the vapors andunvaporized oil and flash distilling the latter by lowering the pressurethereon, dephlegmating the flashed vapors and the vapors removed fromsaid separating zone and combining the resultant reflux condensates,passing the thus combined reflux condensates to a secondary heating zoneand cracking the same therein in the vapor phase at higher temperaturethan that to which the oil is heated in said primary heating zone, andintroducing the vapor phase cracked vapors from said secondary heatingzone into said separating zone.

2. A hydrccarbon oil cracking process which comprises passing the oil ina restricted stream through a primary heating zone and heating the sametherein to cracking temperature under sufficient pressure to maintain asubstantial portion thereof in the liquid phase, discharging the heatedoil into a vapor separating zone and separating the same therein intovapors and unvaporized oil, separately removing the vapors and unva--porized oil and flash distilling the latter by lowering the pressurethereon, dephlegmating the flashed vapors to condense heavier fractionsthereof, passing resultant reflux condensate in direct heat exchangerelation with the vapors removed from said separating zone todephlegmate the latter and combine insufllciently cracked fractionsthereof with said reflux condensate, passing the thus combined refluxcondensates to a secondary heating zone and cracking the same therein inthe vapor phase at higher temperature than that to which the oil isheated in said primary heating zone, and introducing the vapor phasecracked vapors from said secondary heating zone into said separatingzone.

3. A hydrocarbon oil cracking process which comprises passing the oil ina restricted stream through a primary heating zone and heating the sametherein to cracking temperature under sufflcient pressure to maintain asubstantial portion thereof in the liquid phase, discharging the heatedoil into a vapor separating zone and separating the same therein intovapors and unvaporized oil, separately removing the vapors andunvaporized oil and flash distilling the latter by lowering the pressurethereon, dephlegmating the flashed vapors and the vapors removed fromsaid separating zone and combining the resultant reflux condensates,passing the thus combined reflux condensates to a secondary heating zoneand cracking the same therein in the vapor phase at higher temperaturethan that to which the oil isheated in said primary'heating zone,contacting the vapor phase cracked vapors with a cooling oil tosubstantially lower the temperature thereof and introducing the same tosaid separating zone.

4. A hydrocarbonoil cracking process which comprises passing the oil ina restricted stream through a primary heating zone and heating the samethereinto cracking temperature under sufiicient pressure to maintain asubstantial portion thereof in the liquid phase, discharging the heatedoil into a vapor separating zone and separating the same therein intovapors and unvaporized oil, separately removing the vapors andunvaporized oil and flash distilling the latter by lowering the pressurethereon, dephlegmating the flashed vapors to condense heavier fractionsthereof, passing resultant reflux condensate in direct heat exchangerelation with the vapors removed from said separating zone todephlegmate the latter and combine insufliciently cracked fractionsthereof with said reflux condensate, passing the thus combined refluxcondensates to a secondary heating zone and cracking the same therein inthe vapor phase at higher temperature than that to which the oil isheated in said primary heating zone, contacting the vapor phase crackedvapors with a cooling oil to substantially lower the temperature thereofand introducing the same to said separating zone.

5. A hydrocarbon oil cracking process which comprises heating the oil tocracking temperature under pressure in a primary heating zone,separating the heated oil into vapors and unvaporized oil underpresssure, dephlegmating the separated vapors to condense insuflicientlycracked fractions thereof as reflux condensate, condensing thedephlegmated vapors as a product of the process, flash'distilling theunvaporized oil by lowing the pressure thereon, dephlegmating theresultant flashed vapors to condense heavier fractions thereof,combining such condensed heavier fractions with at least a portion ofsaid insufliciently cracked fractions condensed in said dephlegmatingstep and subjecting the mixture to vapor phase cracking in a secondheating zone, and combining the resultant vapor phase cracked productswith products of the first-mentioned zone.

JEAN DELA'I'I'RE SEGUY.

